Page 293 - Mechanical Engineers' Handbook (Volume 2)

284 Analysis, Design, and Information Processing

There is a plethora of literature describing the decision assessment or decision-making part
of the interpretation step of systems engineering. In addition to the discussions in Refs. 1,
2, and 3, excellent discussions are to be found in Refs. 27, 28, and 29.

4.5 The Central Role of Information in Systems Engineering
Information is certainly a key ingredient supporting quality decisions; all of systems engi-
neering efforts are based on appropriate acquisition and use of information. There are three
basic types of information, which are fundamentally related to the three-step framework of
systems engineering:

1. Formulation information
a. Information concerning the problem and associated needs, constraints, and alter-
ables
b. Information concerning the value system
c. Information concerning possible option alternatives
d. Information concerning possible future alternative outcomes, states, and scenarios
2. Analysis information
a. Information concerning probabilities of future scenarios
b. Information concerning impacts of alternative options
c. Information concerning the importance of various criteria or attributes
3. Interpretation information
a. Information concerning evaluation and aggregation of facts and values
b. Information concerning implementation

We see that useful and appropriate formulation, analysis, and interpretation of information
is one of the most important and vital tasks in systems engineering efforts, since it is the
efficient processing of information by the decision-maker that produces effective decisions.
A useful definition of information for our purposes is that it is data of value for decision
making. The decision-making process is influenced by many contingency and environmental
influences. A purpose of the management technology that is systems engineering is to provide
systemic support processes to further enhance efficient decision-making activities.
After completion of evaluation and decision-making efforts, it is generally necessary to
become involved in planning for action to implement the chosen alternative option or the
next phase of a systems engineering effort. More often than not, it will be necessary to iterate
the steps of systems engineering several times to obtain satisfactory closure upon one or
more appropriate action alternatives. Planning for action also leads to questions concerning
resource allocation, schedules, and management plans. There are, of course, a number of
methods from systems science and operations research that support determination of sched-
ules and implementation plans. Each of the steps is needed, with different focus and em-
phasis, at each phase of a systems effort. These phases depend on the particular effort under
consideration but will typically include such phases as policy and program planning, project
planning, and system development.
There are a number of complexities affecting ‘‘rational’’ planning, design, and decision
making. We must cope with these in the design of effective systemic processes. The majority
of these complexities involve systems management considerations. Many have indicated that
the capacity of the human mind for formulating, analyzing, and interpreting complex large-